Author Topic: over attenuation question  (Read 3039 times)

Offline telemarkus

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over attenuation question
« on: July 30, 2017, 12:34:09 AM »
Hi All;

For the last couple of brews I have made, all higher OG (1.060 -1.110) I seem to have a problem with fermatations completing very quickly (reaching targeted FG (1.015-1.030) and still fermenting. when I try to drain the yeast on the conical, I do not have completely flocculated yeast and the beer still wants to ferment going beyond FG targets (raising ABV and affecting body and flavor). in the summer I cannot keep it as cool, but the highest temps I reach are ~ 72F.

What I have ended up doing is transferring the beer direct to keg when it the target FG target but then the beer has always been yeasty and cloudy since I have not been able to let it clear as no final fermentation was in sight from daily measurements.

Yeast starters are always healthy and not excessively over pitched, wort is directly oxygenated with O2 injection for 30 seconds to 1 min. all equipment is thoroughly sanitized every time and I have also noted increased fermentation times even for high grav beer in under a period of 7 days.

Does anyone have a recommendation on what is going on?
« Last Edit: July 30, 2017, 12:42:16 AM by telemarkus »

KellerBrauer

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Re: over attenuation question
« Reply #1 on: July 30, 2017, 06:15:01 AM »
Greetings telemarkus - I don't believe the rapid fermentation is a real concern - depending on the strain of yeast.  What I would be concerned about is the fact that your beer over attenuates. A couple questions come to mind that may help sort this out.

1. What is the Mash profile you're using, temperature time, etc.?
2. What is the Mash pH (after about 10-15 minutes) and what are you using (if anything) to acidify?
3. What happens if you allow the yeast to actually finish, how far past target does it go?
4. What strain of yeast are you using?
5. What are the particulars of the beer in question, OG, Batch Size, Target FG, etc.?  Also, the starter details for this batch might be helpful.

As you know, yeast will continue to gobble up sugars as long as there's sugars available to consume.  So, my initial instinct is that the yeast is simply doing its job and not completed with its work.
« Last Edit: July 30, 2017, 06:23:19 AM by KellerBrauer »

Offline telemarkus

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Re: over attenuation question
« Reply #2 on: July 31, 2017, 01:03:17 AM »
Hello KellerBrauer;

Thanks for taking the time to reply!

Mash Prfile for my last brew (presently fermenting) is an American Brown Imperial Ale. 17G batch. OG 1.067 (FG was supposed to be 1.016, now at 1.014 aug 30, 2017) Mash at 152F for 1 hour, water profile is RO water to start and adjust with 3.5ml of Phosphoric acid pre dough in and 2 tsp of CaCl2 in the mash phase. this is on a RIMS system. pH at 15 mins is 5.33 and end of mash @60 is 5.27 ATC.

I have never let the yeast actually finish (since this problem arose) to see because with past batchs (specifically my Barley wine) that I wanted to come out at 1.030 for body (kept dropping) and I pulled it out to keg. but the problem when is a yeast haze in the beer.

With this particular Brown in the fermenter presently, I am using a non traditional WY 1728 (Scottish) for fermentation cell count was good and viable (post starter) and started in dual erlenmeyers 3 days prior (2 packects of 1728 built with 4 litre starters each) and had 1 min of direct O2 injection prior to pitching.

I guess the biggest problem that I cannot solve is why I have been experiencing the fast over attenuation fermentations lately. the beer certainly is not infected and completely drinkable after I pull the plug, but in styles apart from the Hefes that iI have been brewing lately the yeast haze is bringing out the OCD in me. even after chilling in the keggerator, I have found the yeast still to be in solution suspension for at least half of the keg pouring. I'm confused as to what happened and the only thing i can personally attribute it to is the warmer ferment temps (as all my initial brews on teh new system were in the winter (colder in my cellar for ferment and I actually needed to use a temp controlled heating pad to keep the the set where as now in the summer the ferment temps go beyond the actual rage of where I want it to be)

Offline Oginme

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Re: over attenuation question
« Reply #3 on: July 31, 2017, 05:53:32 AM »
OK, good info in your last post. 

First, every process is a bit different in how much fermentable sugars are developed: your thermometer may be slightly off, the water to grist ratio may lead to better conversion, theyeast if very healthy and active, etc.  There are so many variables to the prediction of final gravity, that I would not sweat a difference of .002 gravity units from the predicted to the actual. 

Your apparent attenuation for the WY1728 ending up at 1.014 is around 79%, which is quite typical and respectable for that yeast, especially for a mash temperature of 152F.  If this is a continuing result of being just under predicted FG by a few points, it may just mean that you need to target a slightly higher mash temperature to reach the intended result.

Now about your fermentation, I don't know how long you are fermenting for in total.  I typically see about 48 to 72 hours of high activity with WY1728 with a slow tapering off and apparent finishing at 84 to 96 hours.  When it takes off, it really goes wild.  That said, there are still some fermentable sugars floating around in the wort/beer and plenty of yeast still in solution.  It is difficult to get the yeast to stop its activity until it exhausts itself.  Wine and mead producers typically use Sodium bisulfite or Potassium sorbate to halt the yeast from consuming all the sugars in order to create a sweeter end product.  Pulling the yeast bed will not stop the activity as there is still plenty of yeast in suspension.  Even clear beer following a few days of cold crashing at around 35F to 40F will have enough yeast to restart fermentation when priming sugar is added.

You don't say if you cold crash your beers or not.  If not, I would highly recommend it to help with slowing down the yeast activity, encouraging the yeast to flocculate and settle out, and to cut back on chill haze proteins which will also flocculate out during the cold crashing.  The other thing I would recommend is to allow the fermentation to go to completion.  While the bulk of activity may be over an a couple of days, vigorous yeasts such as WY1728 leave behind many precursors and byproducts of their orgy of sugar consumption and giving the yeast cells still in solution time to clean these up with improve not only the clarity of your beer but also the shelf life and prevent off flavors.

Another thing that may help with improving your clarity is to check your water profile.  Most yeast strains need a minimum of 50 ppm of Calcium to promote good flocking and settling.  I am not sure in your system where your 2 tsp of CaCl2 gets you with regard to that minimum. Phosphoric acid will also reduce the amount of Calcium in the wort as it will lead to the formation of Calcium phosphate which is relatively insoluble.

The biggest improvement I have made to my beer was getting fermentation temperature control.  Being able to control the temperature of the carboy (not the air around it) lead to improved consistency and control of yeast flavor development.  It also helps to contain very active yeasts such as WY1728 and some of the Belgian yeasts from blowing out the top of my carboys by allowing me to control the initial temperatures in the low 60's and bring it up over time to 68F to 70F to finish off the fermentation.

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Offline telemarkus

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Re: over attenuation question
« Reply #4 on: July 31, 2017, 11:41:53 PM »
Hi Oginme;

Thanks for the reply.

Temps definitely are on as I am measuring them digitally though the RIMS system and also match the mechanical in the kettle. I received the yeast from our local brewery here this time and the brew master said he usually mashes at lower temps when using the 1728 for better attenuation, but yes, certainly in my case the attenuation this time is good.

I agree with you on teh fermentation times, I was seeing about the same thing.

Presently I do not have the capability to cold crash, I am working on setting up a temp controlled freezer. i the winter it is easier for me in my cold room as i can temp control by heat wrapping the conical and then when it turns off I can cold crash, but in the summer i presently have no control and the "cold room" is not so cold!

My assmption with using RO water is that essentially I am starting with a clean slate? that's where the additives come in, but I agree I may have to work on the additions still to tweak it more to get it to spec. I live in the country and we are on a well so that is why I start with RO water, but looking through Gordon Strong's brewing better beer and modern homebrew recipes, he always starts with RO water and his additions are similar to what I was trying to do.

One can always find new tips nd techniques to improve, thanks for taking the time to message!